KR101862398B1 - Display having touch sensor - Google Patents

Abstract

A display device having a touch sensor according to the present invention includes: a display panel having a touch screen on which touch sensors are formed; A Tx driving circuit for supplying a touch driving pulse to the Tx lines of the touch screen; An Rx driving circuit for sampling a voltage of the touch sensors received through the Rx lines of the touch screen and converting the sampling voltage into digital touch data; And a controller for controlling the Rx driving circuit to perform a sampling operation during the low noise period based on the display timing of the digital video data applied to the display panel, And a touch controller that updates the noise profile each time the screen state is switched.

Description

DISPLAY HAVING TOUCH SENSOR [0002]

The present invention relates to a display device having a touch sensor.

User input means has been replaced with a touch screen in a button-type switch in accordance with the trend of lightening and slimming of household appliances and portable information devices. The touch screen refers to a screen that directly touches the screen without the need for another input device, and the use of the touch screen in the overall IT product is expanding as it is used in the handphone market.

The touch screen applied to the display device includes a plurality of touch sensors. The touch sensors may be embedded in a display panel in an in-cell type or may be coupled to a display panel in an on-cell type or an add-on cell type. The touch type is known as a resistive type, a capacitive type, and an electro magnetic type. Among them, the touch sensing part senses the position where the capacitance change has occurred, Is widely used.

A display panel of a display device includes a plurality of pixels, a plurality of data lines to which a data voltage is applied, a plurality of thin film transistors (TFTs) that switch a current path between each pixel and a data line, A plurality of gate lines are formed for supplying scan pulses to the gate electrodes of the TFTs to control on / off operations of the TFTs. The level of the data voltage applied to the data lines continuously changes every time the display image is changed or every time the polarity of the data voltage according to the inversion method is changed. In addition, the potential of the gate lines periodically fluctuates by a scan pulse that is sequentially supplied to select each pixel line to which the data voltage is to be supplied.

The potential variation of the data lines and the gate lines affects the sensing signal of the touch screen and generates sensing noise. The sensing noise is increasing due to the increase of the resistance due to the thickness reduction of the display device and the influence of operation of the high performance semiconductor. As the sensing noise increases, the distortion of the sensing value sampled from the touch screen becomes worse and distortion of the sensing value becomes worse, which may result in undesired touch results. Therefore, in order to remove the sensing noise included in the sensing value, a complicated noise processing process (post-processing process) must be performed after sampling the sensing value from the touch screen. If the post-processing process is prolonged, the touch recognition rate is inevitably lowered.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a display device having a touch sensor capable of mitigating sensing noise in the sampling step.

It is another object of the present invention to provide a display device having a touch sensor that can acquire a noise profile and update sensed state every time a screen state is changed to mitigate sensing noise.

According to an aspect of the present invention, there is provided a display device having a touch sensor, the display device comprising: a display panel having a touch screen on which touch sensors are formed; A Tx driving circuit for supplying a touch driving pulse to the Tx lines of the touch screen; An Rx driving circuit for sampling a voltage of the touch sensors received through the Rx lines of the touch screen and converting the sampling voltage into digital touch data; And a controller for controlling the Rx driving circuit to perform a sampling operation during the low noise period based on the display timing of the digital video data applied to the display panel, And a touch controller that updates the noise profile each time the screen state is switched.

Wherein the touch controller derives the low noise period based on any one of a source output enable signal and a horizontal synchronization signal; The low-noise period indicates a period during which the shake of the common voltage applied to the display panel during one horizontal period is stabilized.

Wherein the Tx driving circuit repeatedly supplies the touch driving pulse to each of the Tx lines; The Rx driving circuit repeatedly samples the voltages of the touch sensors corresponding to the touch driving pulses repeatedly applied a plurality of times and accumulates the sampling voltages.

Wherein the sampling voltages include a first group of sampling voltages sampled at corresponding positions of the display panel when the polarity of the data voltage applied to the display panel is positive and a second group of sampling voltages sampled at corresponding positions of the display panel, And a second group of sampling voltages sampled at corresponding positions of the display panel.

The touch controller determines a current frame analysis register value based on an exclusive OR operation on input digital video data, compares the current frame analysis register value with a previous frame analysis register value determined in a previous frame, .

Wherein the touch controller maintains a noise profile of a previous frame as it is when the current frame analysis register value is equal to the previous frame analysis register value and the screen state is not switched; If the current frame analysis register value differs from the previous frame analysis register value, the noise profile of the previous frame is updated with the noise profile of the current frame based on the sampling voltage, based on the determination that the screen state has been switched.

Wherein the touch controller compensates the digital touch data by referring to the noise profile, extracts touch coordinates by analyzing the compensated touch data by a preset touch recognition algorithm, When the touch state is maintained at a specific point at the time of switching the screen state, the noise profile around the touch coordinates with respect to the specific point is not updated.

Each of the touch sensors is larger than a pixel for image display, and each touch sensor corresponds to a plurality of pixels in the horizontal and vertical directions.

The display device having the touch sensor according to the present invention can avoid serious noise that occurs regularly by driving the touch system during the low noise period in synchronization with the timing signal of one horizontal period period and can alleviate the sensing noise in the sampling step in advance . The reliability of the touch data can be ensured by accumulating the sensing values many times while the low noise period is relatively short.

Further, the display device having the touch sensor according to the present invention compensates the sensing value distortion due to the deviation between the sensing channel or the touch sensor and the sensing value distortion due to the crosstalk of the display image by using the updated noise profile at every screen switching . In addition, when the noise profile is updated, the noise profile around the touch coordinates that maintains the touch state is not updated, so that the touch recognition is possible without losing the touch point or the touch state.

1 is a block diagram showing a display device according to an embodiment of the present invention;
Figures 2 through 4 illustrate various embodiments of a touch screen and a display panel.
5 illustrates a touch screen including a plurality of touch sensors.
6 is a view showing an example of the size of the touch sensor.
7 is a diagram showing a touch system capable of mitigating sensing noise.
Figure 8 shows the voltage of the touch sensors sampled during a low noise period in accordance with a sensing enable signal.
9 is a view sequentially showing an execution sequence of an algorithm for updating a noise profile;
Figures 10A-12B illustrate examples of updating the noise profile.
13 is a view showing simulation results through a MATLAB;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 13. FIG.

1 is a block diagram showing a display device according to an embodiment of the present invention. 2 to 4 are views showing various embodiments of a touch screen and a display panel. FIG. 5 shows a touch screen including a plurality of touch sensors, and FIG. 6 shows an example of the size of the touch sensor. 5 and 6, 'Unit sensor' means one touch sensor.

1, a display device according to an exemplary embodiment of the present invention includes a display panel DIS, display driving circuits 202 and 204, a timing controller 400, a touch screen TSP, touch screen driving circuits 302 and 304, A controller 306, and the like.

The display device of the present invention can be applied to a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), an organic light emitting display , OLEDs, and electrophoresis (EPD) devices. In the following embodiments, a display device is described as a liquid crystal display device as an example of a flat panel display device, but it should be noted that the display device of the present invention is not limited to a liquid crystal display device.

The display panel (DIS) has a liquid crystal layer formed between two substrates. A plurality of gate lines G1 to Gn, n being a natural number) intersecting the data lines D1 to Dm and m are natural numbers and the data lines D1 to Dm are formed on the lower substrate of the display panel DIS, A plurality of TFTs (thin film transistors) formed at intersections of the data lines D1 to Dm and the gate lines G1 to Gn, a plurality of pixel electrodes for charging data voltages to the liquid crystal cells, And storage capacitors connected to the electrodes to maintain the voltage of the liquid crystal cell.

The pixels of the display panel DIS are formed in a pixel region defined by the data lines D1 to Dm and the gate lines G1 to Gn and arranged in a matrix form. The liquid crystal cells of each of the pixels are driven by an electric field applied in accordance with a voltage difference between a data voltage applied to the pixel electrode and a common voltage applied to the common electrode to control the amount of incident light. The TFTs are turned on in response to gate pulses from the gate lines G1 to Gn to supply a voltage from the data lines D1 to Dm to the pixel electrodes of the liquid crystal cell.

The upper substrate of the display panel DIS may include a black matrix, a color filter, and the like. The lower substrate of the display panel DIS may be implemented with a COT (Color Filter On TFT) structure. In this case, the black matrix and the color filter can be formed on the lower substrate of the display panel DIS.

On the upper substrate and the lower substrate of the display panel DIS, a polarizing plate is attached, and an alignment film for forming a pre-tilt angle of the liquid crystal on the inner surface in contact with the liquid crystal is formed. A column spacer for maintaining a cell gap of the liquid crystal cell is formed between the upper substrate and the lower substrate of the display panel DIS.

A backlight unit may be disposed on the back surface of the display panel DIS. The backlight unit is implemented as an edge type or direct type backlight unit, and irradiates the display panel (DIS) with light. The display panel DIS may be implemented in any known liquid crystal mode such as TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode.

The display driving circuit includes a data driving circuit 202 and a scan driving circuit 204, and writes the video data voltage of the input image into the pixels. The data driving circuit 202 converts the digital video data RGB input from the timing controller 400 into an analog positive / negative gamma compensation voltage to generate a data voltage, and supplies the data voltage to the data lines D1- Dm. The scan driving circuit 204 sequentially supplies a gate pulse (or a scan pulse) synchronized with the data voltage to the gate lines G1 to Gn to select a pixel line of the display panel DIS to which the data voltage is written.

The timing controller 400 receives a timing signal such as a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE and a main clock MCLK from an external host system And generates display timing control signals for controlling the operation timings of the data driving circuit 202 and the scan driving circuit 204.

The scan timing control signal is input to a shift register in the scan driver circuit 204, a gate start pulse (GSP) indicating a start horizontal line at which a scan starts in one vertical period in which one screen is displayed, A gate shift clock signal GSC for sequentially shifting the gate driving signal GSP and a gate output enable signal GOE for controlling the output of the scan driving circuit 204.

The data timing control signal includes a source start pulse (SSP), a rising or falling edge indicating a start point of data in one horizontal period in which data for one horizontal line is displayed, A source sampling clock (SSC) for controlling the latch operation, a source output enable signal SOE for controlling the output of the data driving circuit 202, and data to be supplied to the liquid crystal cells of the display panel DIS A polarity control signal POL for controlling the polarity of the voltage, and the like.

The touch screen TSP may be bonded onto the upper polarizer POL1 of the display panel DIS as shown in FIG. 2 or may be formed between the upper polarizer POL1 and the upper substrate GLS1 as shown in FIG. In addition, the touch screen TSP may be formed on the lower substrate as an in-cell type together with the pixel array in the display panel DIS as shown in FIG. 2 to 4, "PIX" means a pixel electrode of a liquid crystal cell, "GLS2" means a lower substrate, and "POL2" means a lower polarizer.

The touch screen TSP includes Tx lines (T1 to Tj, j is a positive integer less than n), Rx lines (R1 to Ri, i being an amount less than m) crossing the Tx lines And a plurality of touch sensors formed at the intersections of the Tx lines T1 to Tj and the Rx lines R1 to Ri. For example, the number of touch sensors may be 108 when 12 Tx lines (T1 to T12) and 9 Rx lines (R1 to R9) are crossed as shown in FIG. Each touch sensor may be formed larger than the pixel. Each touch sensor may correspond to a plurality of pixels in the horizontal and vertical directions. For example, each touch sensor may have a size of 8 pixels by 8 pixels as shown in FIG.

The touch screen driving circuit includes a Tx driving circuit 302 and an Rx driving circuit 304. Such a touch screen driving circuit supplies a touch driving pulse to the Tx lines T1 to Tj and samples the voltages of the touch sensors through the Rx lines R1 to Ri to convert them into digital data. The Tx driving circuit 302 and the Rx driving circuit 304 can be integrated in one ROIC (Read-out IC).

The Tx driving circuit 302 sets a Tx channel to output a touch driving pulse under the control of the touch controller 306. [ The Tx driving circuit 302 supplies the touch driving pulses to the Tx lines T1 to Tj connected to the set Tx channel. The Tx driving circuit 302 may supply the touch driving pulse to the Tx lines Tl through Tj a plurality of times in order to secure a sufficient sensing time. For example, the Tx driving circuit 302 may repeatedly supply the touch driving pulse to the Tx lines T1 to T12 eight times when the touch screen TSP is configured as shown in FIGS. 5 and 6. FIG.

The Rx driving circuit 304 receives the voltage of the touch sensors through the Rx channels connected to the Rx lines R1 to Ri and outputs the sensing voltage to the touch controller 306 for a predetermined period of time according to the sensing enable signal input from the touch controller 306 Sampling. Here, the predetermined period is determined according to the sensing enable signal input from the touch controller 306, and indicates a period during which the noise generated in the display panel DIS is periodically reduced. The Rx driving circuit 304 may repeatedly sample the output of each of the touch sensors within one touch frame in response to the touch drive pulse repeatedly supplied a plurality of times. The Rx driving circuit 304 converts the sampling voltage into digital touch data and transmits the digital touch data to the touch controller 306.

The touch controller 306 is connected to the Tx driving circuit 302 and the Rx driving circuit 304 through an interface such as an I2C bus, a SPI (serial peripheral interface), and a system bus. The touch controller 306 supplies a setup signal to the Tx drive circuit 302 to set the Tx channel to which the touch drive pulse is output. The touch controller 306 generates a sensing enable signal based on the display timing of the digital video data RGB and supplies the sensed enable signal to the Rx driving circuit 304 to adjust the sampling timing of the voltages of the touch sensors . The touch controller 306 acquires a noise profile and updates the noise profile based on the update enable signal every time the screen state is switched (that is, every time the display image is changed). The touch controller 306 additionally alleviates the sensing noise by using the updated noise profile for the noise compensation remaining in the digital touch data input from the Rx driving circuit 304. The touch controller 306 analyzes the noise-compensated digital touch data using a preset touch recognition algorithm to calculate a touch coordinate value. The coordinate value data of the touch position output from the touch controller 306 is transmitted to an external host system. The host system executes the application program indicated by the coordinate value of the touch position.

Fig. 7 shows a touch system capable of mitigating sensing noise. 8 shows that the voltage of the touch sensors is sampled during the low noise period according to the sensing enable signal.

7 and 8, the touch system capable of mitigating sensing noise includes a sampling unit 3041, an analog-to-digital conversion unit 3042, and a touch controller 306 provided in the Rx driving circuit 304 A noise enable signal generating unit 3063, a noise profile generating unit 3064, a noise compensating unit 3065, and a touch coordinate value extracting unit 3066. The synchronization enable signal generating unit 3062, the update enable signal generating unit 3063, .

The synchronization unit 3061 synchronizes a timing signal, e.g., a source output enable signal SOE or a horizontal synchronization signal Hsync, generated every one horizontal period 1H to avoid noise mixed in from the display panel DIS (P2) during one horizontal period (1H). In FIG. 8, 'P1' is a high noise period with a large noise influence. The low noise period P2 is allocated after the high noise period P1 in one horizontal period (1H).

The sensing enable signal generator 3062 generates a sensing enable signal so that a sampling operation can be performed during the low noise period P2 derived from the synchronizer 3061. [

The update enable signal generator 3063 determines whether the screen state is switched through the comparison operation of the digital video data RGB and generates an update enable signal capable of updating the noise profile in response to the switching of the screen state do.

The sampling unit 3041 receives the voltage Vsen of the touch sensors through the Rx channels and outputs the sensing voltage Vsen to the low noise section (Vsen) according to the sensing enable signal input from the sensing enable signal generator 3062 P2). The noise source having the greatest influence on the touch screen TSP is the source output enable signal SOE or the common voltage Vcom generated synchronously with the rising edge (or the falling edge) of the horizontal synchronizing signal Hsync It is a shake. Such a noise can be avoided by performing the sampling operation in the low noise period P2 in which the fluctuation of the common voltage Vcom is stabilized during one horizontal period 1H. This sampling method is based on the experimental results that many of the many noise are generated regularly. Of course, there is random noise that can occur in analog devices, but this is relatively small and negligible.

However, the low noise period P2 is usually 10 占 퐏 or less, which is not a sufficient sensing time. In order to overcome this, the sampling unit 3041 repeats the output of the touch sensors a plurality of times (for example, 8 times) corresponding to the touch drive pulse (e.g., Nth Tx) supplied repeatedly a plurality of times And accumulate the sampling voltages S1 to S8. At this time, the sampling voltages S1 to S8 are divided into the first group S1, S3, and S5 in consideration of the inversion method in which the polarity of the data voltage Vdata charged in the display panel DIS is inverted in units of one horizontal line. , S7) and the second group (S2, S4, S6, S8). The sampling voltages S1, S3, S5 and S7 of the first group are set so that the positive (+) data voltage Vdata is applied to the display panel DIS when a touch And the second group of sampling voltages S2, S4, S6 and S8 is a voltage corresponding to the display panel DIS when the negative data voltage Vdata is charged to the display panel DIS Position of the touch sensor.

The analog-to-digital converter 3042 receives the sampling voltages from the sampling unit 3041, converts the sampling voltages into analog-digital data, and generates digital touch data.

The noise profile generation unit 3064 receives sampling voltages from the sampling unit 3041, and generates a noise profile based on the sampling voltages. The noise profile indicates a noise analysis value used for noise compensation and is very useful for compensating a sensing value distortion due to a deviation between a receiving channel or a touch sensor and also compensates for sensing value distortion due to crosstalk of a display image It is also very useful for. When the update enable signal is input, the noise profile generation unit 3064 updates the noise profile generated with the new noise profile based on the sampling voltages input from the sampling unit 3041 at the time of switching the screen state. Updating the noise profile for each transition of the screen state has the effect of increasing the noise compensation accuracy. However, the noise profile generation unit 3064 does not update the noise profile around the touch coordinates when the touch state is maintained when the screen state is switched. The description of the operation of updating the noise profile will be described in detail later with reference to the algorithm of FIG.

The noise compensating unit 3065 compensates the digital touch data input from the analog-to-digital converting unit 3042 based on the noise profile from the noise profile generating unit 3064 to remove the noise influence remaining in the touch data.

The touch coordinate value extraction unit analyzes the touch data from which the noise has been removed by a preset touch recognition algorithm to calculate a touch coordinate value. The touch coordinate value is fed back to the noise profile generation unit 3064 to update the noise profile.

Figure 9 shows an algorithm for updating the noise profile. Such an algorithm is embedded in the touch controller 306. [

This algorithm detects the start of the current frame based on a timing signal such as a vertical synchronizing signal and at the same time sets the operation register X and the analysis register A for the digital video data in the current frame to an initial value 00000000 " for bit data). (S1)

This algorithm sequentially performs exclusive OR (XOR) on the input data until all the digital video data for one line is input based on the timing signal such as the horizontal synchronizing signal and the data enable signal, (S2, S3). In the current frame operation register X, exclusive OR (XOR) operation results for input data are sequentially stored for each line.

This algorithm sequentially performs exclusive OR (XOR) on the stored values of the current frame operation register X for each line until all the digital video data for one frame is input based on a timing signal such as a vertical synchronizing signal, ) To continuously update the stored value of the current frame analysis register A. (S4, S5)

When the current frame ends, the algorithm compares the stored value of the current frame analysis register A updated until then with the stored value of the previous frame analysis register A 'stored in the previous frame, It is determined whether or not the screen is the same as the screen in step S6.

If the stored value of the current frame analysis register A and the stored value of the previous frame analysis register A 'are the same, the algorithm maintains the noise profile of the previous frame as it is determined that the screen state has not been switched. On the other hand, if the stored value of the current frame analysis register A differs from the stored value of the previous frame analysis register A ', the algorithm updates the noise profile of the previous frame to a new noise profile, do. Then, the stored value of the current frame analysis register A is reset to the stored value of the previous frame analysis register A 'for operation in the next frame (S7)

This algorithm compensates the digital touch data by referring to the noise profile, and extracts the touch coordinate values by analyzing the compensated touch data by the touch recognition algorithm (S8, S9, S10)

This algorithm does not update the noise profile around the touch coordinates when the touch state is maintained when the screen state is switched (S11)

According to the present invention, when the touch state is continuously maintained when the screen state is changed, the noise profile around the touch coordinates is not updated so that the effect of accurately recognizing the touch point or the touch state can be obtained have. Examples of this will be described later in detail with reference to FIGS. 10A to 12B.

The amount of exclusive OR operation for the line data and the amount of operation for performing the exclusive OR operation on these values for one frame are not many. Therefore, this algorithm can be a useful method for determining whether the current frame image has a change from the previous frame image. This algorithm can be applied not only to motion images but also to still images, and does not cause a decrease in the touch rate due to noise profile updating.

Figures 10A-12B illustrate examples of updating the noise profile.

FIGS. 10A and 10B show side effects when updating the noise profile around the touch coordinates when the touch state is maintained at the same position continuously at the time of switching the screen state.

Referring to FIG. 10A, a noise profile is set based on sampling voltages in an initial screen display state. In this noise profile, the sensed value of the touched portion changes. (Noise + Touch) When the profile is calibrated using the noise profile, only the profile of the touch part remains.

Referring to FIG. 10B, when a frame is changed and another image is displayed on the screen, the noise profile is updated to a different value. At this time, if the touch profile is updated to the noise profile around the touch coordinates in the state where the touch is maintained before and after the screen change, the sensing value of the touched portion is recognized as the noise profile. That is, the updated noise profile and the (noise + touch) profile become equal to each other. Therefore, when the (noise + touch) profile is corrected to the updated noise profile, the touched portion disappears. This is a side effect caused by a false update of the noise profile.

11A and 11B show the effect when the noise profile around the touch coordinates is not updated when the touch state is maintained at the same position continuously at the time of switching the screen state.

Fig. 11A is the same as that described in Fig. 10A.

Referring to FIG. 11B, when the frame is changed and another image is displayed on the screen, the noise profile is updated to a different value, but the noise profile around the touch coordinates is not updated but maintained at the previous value. The (noise + touch) profile is generated by reflecting the change in the sensed value of the touched portion in the updated noise profile. When the (noise + touch) profile is corrected using the updated noise profile, only the profile of the touch portion is left. As a result, it becomes possible to effectively update the noise profile without losing the touch point.

12A and 12B show the effect when the noise profile around the touch coordinates is not updated when the touch state is continuously maintained by changing the position at the time of changing the screen state.

12A is the same as that described in Fig. 10A.

Referring to FIG. 12B, when a frame is changed and another image is displayed on the screen, the noise profile is updated to a different value, and the noise profile around the first touch coordinates is not updated but maintained at the previous value. The (noise + touch) profile is generated by reflecting the change in the sensing value around the second touch coordinates in the updated noise profile. When the (noise + touch) profile is corrected using the updated noise profile, only the touch profile for the second touch coordinates is left. As a result, it becomes possible to effectively update the noise profile without losing the touch point.

Fig. 13 shows a simulation result through Matlab.

FIG. 13A shows an example of a noise profile, FIG. 13B shows a non-compensated sensing data, FIG. 13C shows compensated sensing data, ) Shows the binarized compensation sensing data, respectively.

Referring to FIG. 13, when sensing data is obtained repeatedly in a low noise region as in the present invention and noise compensation is performed using a noise profile that is updated every time the screen state is changed (except for touch coordinates) The touch point can be effectively distinguished from other parts.

As described above, the display device having the touch sensor according to the present invention avoids the serious noise that occurs regularly by driving the touch system during the low noise period in synchronization with the timing signal of one horizontal period, Can be mitigated. The reliability of the touch data can be ensured by accumulating the sensing values many times while the low noise period is relatively short.

Further, the display device having the touch sensor according to the present invention compensates the sensing value distortion due to the deviation between the sensing channel or the touch sensor and the sensing value distortion due to the crosstalk of the display image by using the updated noise profile at every screen switching . In addition, the present invention does not update the noise profile around the touch coordinates when the noise profile is updated while the touch is maintained, so that the touch recognition is possible without losing the touch point or the touch state.

Furthermore, the display device having the touch sensor according to the present invention can increase the touch recognition rate by simplifying the post-processing process of the touch data by alleviating the sensing noise. The display device having the touch sensor according to the present invention is useful for a touch sensor structure which is vulnerable to noise such as an on-cell type of an in-cell type or an in-plane switching (IPS) mode .

DIS: display panel 202: data driving circuit
204: scan driving circuit 302: Tx driving circuit
304: Rx driving circuit 306: Touch controller
400: Timing controller 3041: Sampling unit
3042: Analog-to-digital conversion section 3061: Synchronization section
3062: sensing enable signal generator 3063: update enable signal generator
3064: Noise Profile Generation Unit 3065: Noise Compensation Unit
3066: touch coordinate value extracting unit

Claims (8)

A display panel having a touch screen formed with touch sensors;
A Tx driving circuit for supplying a touch driving pulse to the Tx lines of the touch screen;
An Rx driving circuit for sampling a voltage of the touch sensors received through the Rx lines of the touch screen and converting the sampling voltage into digital touch data; And
The Rx driving circuit controls the Rx driving circuit to perform a sampling operation during a low noise period in which the shake of a common voltage applied to the display panel is stabilized during one horizontal period, obtains a noise profile based on the sampling voltage, And a touch controller for updating the noise profile. The method according to claim 1,
Wherein the touch controller derives the low noise period based on any one of a source output enable signal and a horizontal synchronization signal. The method according to claim 1,
Wherein the Tx driving circuit repeatedly supplies the touch driving pulse to each of the Tx lines;
Wherein the Rx driving circuit repeatedly samples the voltage of the touch sensors a plurality of times corresponding to the touch driving pulse repeatedly applied a plurality of times, and accumulates the sampling voltages. The method of claim 3,
Wherein the sampling voltages include a first group of sampling voltages sampled at corresponding positions of the display panel when the polarity of the data voltage applied to the display panel is positive and a second group of sampling voltages sampled at corresponding positions of the display panel, And a second group of sampling voltages sampled at corresponding positions of the display panel. The method according to claim 1,
The touch controller determines a current frame analysis register value based on an exclusive OR operation on input digital video data, compares the current frame analysis register value with a previous frame analysis register value determined in a previous frame, The display device comprising: a touch sensor; 6. The method of claim 5,
The touch controller includes:
If the current frame analysis register value is the same as the previous frame analysis register value, maintaining the noise profile of the previous frame as it is,
If the current frame analysis register value is different from the previous frame analysis register value, updating the noise profile of the previous frame with the noise profile of the current frame based on the sampling voltage, . The method according to claim 1,
The touch controller includes:
Compensating the digital touch data by referring to the noise profile, extracting touch coordinates by analyzing the compensated touch data by a preset touch recognition algorithm;
Wherein when the touch state is maintained at a specific point at the time of switching the screen state, the noise profile around the touch coordinates with respect to the specific point is not updated. The method according to claim 1,
Wherein each of the touch sensors is larger than a pixel for image display, and each of the touch sensors corresponds to a plurality of pixels in the horizontal and vertical directions.

Images